The proposed use of a pressurized barrier sealant fluid between two seals for fluid control apparatus such as pumps, valves and the like is generally known. For example, pressurized dynamic shaft sealing arrangements are disclosed in U.S. Pat. No. 5,746,435 to Arbuckle, U.S. Pat. No. 6,161,835 to Arbuckle, U.S. Pat. No. 5,772,216 to Bredemeyer and U.S. Pat. No. 5,607,165 to Bredemeyer. Such pressurized dynamic sealing arrangements may be used in the process gas industry for valves and the like to better ensure that process gas (e.g. natural gas, gaseous fuel, etc.) does not leak or cause a hazardous external environment.
These patents disclose that use of pressurized barrier sealant provides opposing axial fluid forces on two spaced apart seals. In these arrangements, the barrier sealant fluid pressure is typically greater than the process gas pressure such that if leakage is to occur, most or all of the leakage would be the barrier sealant rather than process gas. Indicating mechanisms are disclosed in these patents that indicate whether sealant leakage is occurring.
The problem with the concepts disclosed in the foregoing patents is that the concepts appear to be complex and costly to implement. More specifically, these proposals have complex plumbing arrangements, are not practical to structurally implement, and/or require numerous complex components for establishing a preload barrier. Further, the indicating mechanism disclosed in at least some of these patents may have accuracy problems, may not readily indicate the exact source of the problem and/or may be difficult or impractical to implement in the field or across different applications. Finally as will be appreciated by the present invention, these prior art concepts are subject to potential premature failure or leakage.